This vacuum table project was just an experiment to see if a design like
this would work. I think it turned out pretty nice, and performed well considering I did zero research before designing and making it.
The basic design goals that I was working around was to make it as thin
as possible while maintaining enough vacuum clamping ability to hold a variety of materials down. I also wanted to be able to machine the entire top of the work area, so that it could be machine level. Finally, I wanted to be able to have it bolt directly to my aluminum table extrusion. For the most part I hit most of my design goals without too much problems. I still need to mill some countersunk bolt holes on the back to get rid of the two clamps on the back side, but it works great so long as you remember to put those clamps on the backside of the fixture.
I tried a couple of jobs using the vacuum table. One of them with brass shim stock, and the other with some 1/4" thick oak. The shim stock didn't work so well, but I think that with a little bit of fussing I might be able to get it to work. The wood on the other hand, didn't give me any problems at all. Anyways, here's a couple more pictures, and a video I made documenting the project.